1. Field of the Invention
The present invention relates to orthopaedic reamer assemblies, and, more particularly, to drivers used with orthopaedic reamer assemblies.
2. Description of the Related Art
The small incision that surgeons are using for minimally invasive hip surgery make it difficult to insert a current full size hemispherical acetabular reamer through the small incision. However, the full size hemispherical acetabular reamer cuts a full hemispherical shape in the acetabulum with minimal wobbling and therefore provides an excellent preparation for the hip joint prosthesis.
Orthopaedic reamers are known that cut off opposing segments of the hemispherical shell of the reamer. The resulting reamer, while having a reduced profile in a certain orientation, is no longer rotationally symmetric. The lack of rotational symmetry can cause vibration and wobbling of the reamer when in use. Such a cut-down reamer design can cut an irregular cavity in the acetabulum, for example, during hip joint prosthesis. An irregular cavity in the acetabulum can reduce the expected lifetime of the hip joint prosthesis, cause discomfort for the patient and increase the wear in the artificial joint, among other problems.
An expanding reamer is known for surgical reaming of the acetabulum in hip surgery. The reamer includes a head with a convex end adapted to seat in a previously prepared concavity in the central part of the acetabulum. This head pivotably mounts a set of radially expansive blades. The reamer is telescopically mounted on the end of a rotary drive shaft, and the drive shaft mounts a cam actuator which engages cam elements to expand the cutters progressively in response to axial thrust exerted on the drive shaft by a surgeon with the reamer head seated in the acetabulum. A spring is used to contract the cutters when the reaming operation is interrupted. Such a reamer has many moving parts associated therewith, adding to the cost of the reamer, making the reamer difficult to clean and sterilize and reducing the reliability of the reamer.
What is needed in the art is a device and method for using a full size hemispherical acetabular reamer, of a reliable design, in minimally invasive hip surgery consistent with the small incision thereof.